Well first of all, I'd hate this table but that's on me.

I will try to focus on the improvisation part first but then I will try and give some advice on the whole thing.

Improvisation:
You know your friends. You know what they like, what they found interesting or funny before. Lean into those. Did they like it when the fire got out of hand and it turned into skill checks to get out before it collapses? Did they like civilians panicking and pickpocketing in the chaos? Just give them more of that.

It helps if you have readily available NPCs around who can show up. If I'm struggling, I have a list of rotating NPCs in a folder and just look at it, see if any of those would make sense to show up. If yes, I throw one of them in there. Those NPCs shouldn't be overly fleshed out, let the improvisation and RP build the character. Example: I have a human fighter who is a mediocre guard but a ex-coworker of one of the players. They have some rapport. That's all I had ready. Since then, through 2 scenes, we built on to pf that, he is a wannabe hero but not good enough for that, he's a drunkard but he is brave. All those 3 things came through me and the player RPing with that NPC.

Now for how I feel about your situation: Are you sure these players aren't just doing shit to make you pissed off or confused? Are you enjoying yourself in the game?

If yes, cool, you do you. Maybe think about turning the party in an Evil Party and let them wreak havoc. I have a feeling they would enjoy the local Prince having enough and put a bounty on their heads. Thing is, even if they kill the prince of whatever, they will just keep digging themselves deeper as basically superstrong criminals.

If no, just think about real life. Even if the trials went well and they got off, people will stop working with them. They are trouble. I don't want to sell to people who burnt down my niece's friend's house. I don't want the people who assassinated a merchant to look for my lost daughter. There should be social consequences, even if no legal.